Blockade of CD73 delays glioblastoma growth by modulating the immune environment.

Immunotherapy as an approach for cancer treatment is clinically promising. CD73, which is the enzyme that produces extracellular adenosine, favors cancer progression and protects the tumor from immune surveillance. While CD73 has recently been demonstrated to be a potential target for glioma treatment, its role in regulating the inflammatory tumor microenvironment has not yet been investigated. Thus, this study explores the immunotherapeutic value of the CD73 blockade in glioblastoma. The immuno-therapeutic value of the CD73 blockade was evaluated in vivo in immunocompetent pre-clinical glioblastoma model. As such, glioblastoma-bearing rats were nasally treated for 15 days with a siRNA CD73-loaded cationic-nanoemulsion (NE-siRNA CD73R). Apoptosis was determined by flow cytometry using Annexin-V staining and cell proliferation was analyzed by Ki67 expression by immunohistochemistry. The frequencies of the CD4+, CD8+, and CD4+CD25highCD39+ (Treg) T lymphocytes; CD11b+CD45high macrophages; CD11b+CD45low-microglia; and CD206+-M2-like phenotypes, along with expression levels of CD39 and CD73 in tumor and tumor-associated immune cells, were determined using flow cytometry, while inflammatory markers associated with tumor progression were evaluated using RT-qPCR. The CD73 blockade by NE-siRNA CD73 was found to induce tumor cell apoptosis. Meanwhile, the population of Tregs, microglia, and macrophages was significantly reduced in the tumor microenvironment, though IL-6, CCL17, and CCL22 increased. The treatment selectively decreased CD73 expression in the GB cells as well as in the tumor-associated-macrophages/microglia. This study indicates that CD73 knockdown using a nanotechnological approach to perform nasal delivery of siRNA-CD73 to CNS can potentially regulate the glioblastoma immune microenvironment and delay tumor growth by inducing apoptosis.

CD73 as a target to improve temozolomide chemotherapy effect in glioblastoma preclinical model.

Glioblastoma is the most devastating primary brain tumor and effective therapies are not available. Treatment is based on surgery followed by radio and chemotherapy with temozolomide (TMZ), but TMZ increases patient survival only by 2 months. CD73, an enzyme responsible for adenosine production, emerges as a target for glioblastoma treatment. Indeed, adenosine causes tumor-promoting actions and CD73 inhibition increases sensitivity to TMZ in vitro. Here, a cationic nanoemulsion to nasal delivery of siRNA CD73 (NE-siRNA CD73) aiming glioblastoma treatment was employed alone or in combination with TMZ. In vitro, two glioblastoma cell lines (C6 and U138MG) with a chemo-resistant profile were used. Treatment alone with NE-siRNA CD73 reduced C6 and U138MG glioma cell viability by 70% and 25%, respectively. On the other hand, when NE-siRNA + TMZ combined treatment was employed, a reduction of 85% and 33% of cell viability was observed. Notably, treatment with NE-siRNA CD73 of glioma-bearing Wistar rats reduced tumor size by 80%, 60% more than the standard chemotherapy with TMZ, but no synergistic or additive effect was observed in vivo. Additionally, NE-siRNA CD73, TMZ or combined therapy decreased adenosine levels in liquor confirming the importance of this nucleoside on in vivo GB growth. Finally, no hemolytic potential was observed. These results suggest that nasal administration of NE-siRNA CD73 exhibits higher antiglioma effect when compared to TMZ. However, no synergistic or additive in vivo was promoted by the therapeutic regimen employed in this study.

Nasal Administration of Cationic Nanoemulsions as CD73-siRNA Delivery System for Glioblastoma Treatment: a New Therapeutical Approach.

Glioblastoma is the most devastating primary brain tumor. Effective therapies are not available, mainly due to high tumor heterogeneity, chemoresistance, and the difficulties imposed by blood-brain barrier. CD73, an enzyme responsible for adenosine (ADO) production, is overexpressed in cancer cells and emerges as a target for glioblastoma treatment. Indeed, ADO causes a variety of tumor-promoting actions, particularly by inducing tumor immune escape, whereas CD73 inhibition impairs tumor progression. Here, a cationic nanoemulsion to deliver CD73siRNA (NE-siRNA CD73R) via nasal route aiming glioblastoma treatment was developed. NE-siRNA CD73R was uptaken by glioma cells in culture, resulting in a parallel 60-80% decrease in AMPase activity and 30-50% in cell viability. Upon nasal delivery, NE-siRNA CD73R was detected in rat brain and serum. Notably, treatment with CD73siRNA complexes of glioma-bearing Wistar rats reduced tumor growth by 60%. Additionally, NE-siRNA CD73R treatment decreased 95% ADO levels in liquor and tumor CD73 expression, confirming in vivo CD73 silencing. Finally, no toxicity was observed in either primary astrocytes or rats with this cationic nanoemulsion. These results suggest that nasal administration of cationic NE as CD73 siRNA delivery system represents a novel potential treatment for glioblastoma. Graphical Abstract Glioblastoma is the most common and devastating form of primary brain tumor. CD73, a protein involved in cell-cell adhesion and migration processes and also responsible for extracellular adenosine (ADO) production, is overexpressed by glioma cells and emerges as an important target for glioma treatment. Indeed, ADO participates in tumor immune escape, cell proliferation, and angiogenesis, and CD73 inhibition impairs those processes. Here, a cationic nanoemulsion to deliver CD73 siRNA (NE-siRNA CD73R) via nasal route aiming glioblastoma treatment was developed. NE-siRNA CD73R knockdown in vitro and in vivo CD73. Upon nasal delivery of NE-siRNA CD73R, the treatment markedly reduced tumor volume by 60% in a rat preclinical glioblastoma model. The treatment was well tolerated, and did not induce kidney, liver, lung, olfactory, bone marrow, or behavior alterations. These results indicate that the nasal administration of NE as a CD73 siRNA delivery system offered an efficient means of gene knockdown and may represent a potential alternative for glioblastoma treatment.

CD73 Downregulation Decreases In Vitro and In Vivo Glioblastoma Growth.

Glioblastoma is the worst and most common primary brain tumor. Here, we demonstrated the role of CD73, an enzyme responsible for adenosine (ADO) production, in glioblastoma progression. ADO increased glioma cell viability via A1 receptor sensitization. CD73 downregulation decreased glioma cell migration and invasion by reducing metalloproteinase-2 and vimentin expression and reduced cell proliferation by 40%, which was related to necrosis and sub-G1 phase blockage of cell cycle. Those effects also involved the stimulation of Akt/NF-kB pathways. Additionally, CD73 knockdown or enzyme inhibition potentiated temozolomide cytotoxic effect on glioma cells by decreasing the IC50 value and sensitizing cells to a non-cytotoxic drug concentration. CD73 inhibition also decreased in vivo rat glioblastoma progression. Delivery of siRNA-CD73 or APCP reduced tumor size by 45 and 40%, respectively, when compared with control. This effect was followed by a parallel 95% reduction of ADO levels in cerebrospinal fluid, indicating the role of extracellular ADO in in vivo glioma growth. Treatment did not induce systemic damage or mortality. Altogether, we conclude that CD73 is an interesting target for glioblastoma treatment and its inhibition may provide new opportunities to improve the treatment of brain tumors. Graphical Abstract ᅟ.

Protective effect of a hydrogel containing Achyrocline satureioides extract-loaded nanoemulsion against UV-induced skin damage.

Achyrocline satureioides is a medicinal plant widely used in South America that exhibits a well-documented antioxidant activity. Such activity has been related to their main aglycone flavonoids quercetin, luteolin, and 3-O-methylquercetin (3MQ). This study addresses the development of antioxidant hydrogels containing an A. satureioides extract-loaded nanoemulsions aimed at topical application. The systems investigated were A. satureioides extract-loaded nanoemulsions (ASNE) obtained by spontaneous emulsification procedure formulated in semisolid hydrogels composed of Carbopol® Ultrez 20 (HASNE). Hydrogels exhibit a non-Newtonian pseudoplastic behavior. A higher release of 3MQ from ASNE (3.61µg/cm(2)/h) was observed when compared with HASNE (2.83µg/cm(2)/h). Different parameters that may have an influence on the retention of flavonoids into the skin were investigated by using a Franz-type diffusion cells. Indeed, the amount of formulation applied on donor compartment was found to play a crucial role. At the optimized conditions, retention of approximately 2µg/cm(2) of flavonoids was detected into the skin. A higher retention of 3MQ was detected (approximately 1.0µg/cm(2)) in comparison with the other flavonoids. Finally, a protection the porcine ear skin by formulations, against oxidative stress generated by UVA/UVB light was demonstrated by means of TBARS, protein carbonylation, and protein thiol content assays. The overall results showed the potential of the formulations developed in this study for the prevention of oxidative stress on the skin.

Assessing an imidazolium salt's performance as antifungal agent on a mouthwash formulation.

AIMS: This study demonstrates the development of a mouthwash formulation containing the imidazolium salt (IMS) 1-n-hexadecyl-3-methylimidazolium chloride (C16 MImCl), considering its stability and efficacy against Candida sp. Biofilm formation. METHODS AND RESULTS: A variety of in vitro test methods were applied, assessing contaminated acrylic resin strip specimens before and after applying the mouthwash formulations. The formulation using C16 MImCl presented a similar antibiofilm activity to cetylpyridinium chloride one and a commercial mouthwash, but at a 10 times lower concentration. Scanning electron microscopy imaging demonstrated that the selected mouthwash preparation fully destroys the biofilm cells, while with the hypoallergenicity test no irritant effect was observed in ex vivo model. CONCLUSIONS: The results presented herein indicate a high potential for imidazolium salts application as mouthwash agents that can eliminate Candida biofilm growth at very low concentrations. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates a new and effective antibiofilm formulation containing the IMS C16 MImCl. These findings suggest the IMS' use as mouthwash formulations active ingredient against Candida biofilms on oral surfaces, as it outperforms the often used cetylpyridinium chloride at a 10 times lower concentration.

In Vitro Evaluation of Mucosa Permeation/Retention and Antiherpes Activity of Genistein from Cationic Nanoemulsions.

In this report, we described the genistein distribution on excised porcine esophageal mucosa from cationic nanoemulsions, as well as the anti-HSV-1 activity against a viral strain resistant to acyclovir. Genistein-loaded cationic nanoemulsions were prepared by spontaneous emulsification. This procedure yielded monodisperse nanoemulsions exhibiting a mean droplet size of approximately 200-300 nm. Hydroxyethyl cellulose (HEC) was added at the end of the manufacturing process as a thickening agent (at 3%). Such formulations exhibit a non-Newtonian pseudoplastic behavior. The addition of HEC significantly reduces the genistein flux through excised porcine mucosa specimens as compared with values elicited by nanoemulsions before thickening. Furthermore, a significant increase of genistein retention in mucosa was observed as compared to the genistein propylene glycol solution, as illustrated by confocal fluorescence microscopy images. Formulations exhibited antiherpetic activity in vitro against HSV-1 (strain 29R). Taken together, these results suggest that these formulations have promising potential to be used topically for herpes infections.

Antiherpes evaluation of soybean isoflavonoids.

The antiviral effects of soybean isoflavonoids have been investigated recently, especially those of genistein. It has been reported that this isoflavone is able to inhibit herpes simplex virus (HSV) replication, which is associated with skin and epithelial mucosa infections. The treatment of these infections with antiherpes drugs has resulted in the emergence of resistant viral strains. Based on this evidence, the aim of this study was to investigate the anti-HSV effects of soybean isoflavonoids: daidzein, genistein, glycitein, and coumestrol. Genistein and coumestrol inhibited HSV-1 (KOS and 29R strains, which are acyclovir sensitive and acyclovir resistant, respectively) and HSV-2 (333 strain) replication, whereas no antiviral effects were detected for daidzein and glycitein. The mechanisms of action were evaluated by different methodological strategies. Coumestrol affected the early stages of viral infection, and both compounds were able to reduce HSV-1 protein expression, as well as HSV-2 cell-to-cell spread.

Simultaneous quantification of flavonoids from Achyrocline satureioides by a polar-reversed phase LC method--application to skin permeation/retention studies.

A selective and sensitive polar-reversed phase LC method was validated for simultaneous quantification of the main Achyrocline satureioides flavonoids (quercetin, luteolin, and 3-O-methylquercetin) in skin samples after permeation/retention studies from topical nanoemulsions. The method was linear in a range of 0.25 to 10.0 microg/mL exhibiting a coefficient of determination higher than 0.999 for all flavonoids. No interference of the nanoemulsion excipients or skin components was observed in the retention times of all flavonoids. The R.S.D. values for intra- and inter-day precision experiments were lower than 6.73%. Flavonoids recovery from nanoemulsions and skin matrices was between 90.05 and 109.88%. In a permeation/retention study with porcine ear high amount of 3-O-methylquercetin was found in the skin sample (0.92 +/- 0.22 microg/g) after two hours. The proposed method was suitable to quantify the main flavonoids of A. satureioides in skin permeation/retention studies from topical nanoemulsions.

Selective cytotoxicity and apoptosis induction in glioma cell lines by 5-oxygenated-6,7-methylenedioxycoumarins from Pterocaulon species.

The coumarins 5-methoxy-6,7-methylenedioxycoumarin 1 5-(3-methyl-2-butenyloxy)-6,7-methylenedioxycoumarin 2 and 5-(2,3-dihydroxy-3-methylbutyloxy)-6,7-methylenedioxycoumarin 3 isolated from Pterocaulon species showed significant cytotoxicity against two glioma cells lines. Compound 1 presented IC(50) values of 34.6 µM and 31.6 µM against human (U138-MG) and rat (C6) glioma cells, respectively, and this compound was at least two times more potent than compounds 2 and 3. This result could be explained by the planar conformation adopted by 1 through a non-classical hydrogen bond between a hydrogen of the methoxy and the oxygen of the methylenedioxy groups. Another important finding was that the cytotoxic effect induced by 1 in glioma cells was not observed in organotypic cultures, indicating a selective cytotoxicity for tumor cells.

Micellar aggregates of saponins from Chenopodium quinoa: characterization by dynamic light scattering and transmission electron microscopy.

Entire seeds of Chenopodium quinoa Willd are a rich protein source and are also well-known for their high saponin content. Due to their amphiphily quinoa saponins are able to form intricate micellar aggregates in aqueous media. In this paper we study the aggregates formed by self-association of these compounds from two quinoa saponin fractions (FQ70 and FQ90) as well as several distinctive nanostructures obtained after their complexation with different ratios of cholesterol (CHOL) and phosphatidylcholine (PC). The FQ70 and FQ90 fractions were obtained by reversed-phase preparative chromatography. The structural features of their resulting aggregates were determined by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). Novel nanosized spherical vesicles formed by self-association with mean diameter about 100-200 nm were observed in FQ70 aqueous solutions whereas worm-like micelles an approximate width of 20 nm were detected in FQ90 aqueous solutions. Under experimental conditions similar to those reported for the preparation of Quillaja saponaria ISCOM matrices, tubular and ring-like micelles arose from FQ70:CHOL:PC and FQ90:CHOL:PC formulations, respectively. However, under these conditions no cage-like ISCOM matrices were observed. The saponin composition of FQ70 and FQ90 seems to determine the nanosized structures viewed by TEM. Phytolaccagenic acid, predominant in FQ70 and FQ90 fractions, is accountable for the formation of the nanosized vesicles and tubular structures observed by TEM in the aqueous solutions of both samples. Conversely, ring-like micelles observed in FQ90:CHOL:PC complexes can be attributed to the presence of less polar saponins present in FQ90, in particular those derived from oleanolic acid.

LC analysis of coumestrol incorporated into topical lipid nanoemulsions.

A simple, rapid, and sensitive LC method to determine coumestrol incorporated in the lipid nanoemulsions was validated. The analyses were performed at room temperature on a reversed-phase C18 column using a mobile phase composed of methanol/water with 0.1% trifluoracetic acid (70:30, v/v) at 0.8 mL min(-1). The detection was carried out on a UV detector at 343 nm. The linearity, in the range of 0.1-6.0 microg/mL, presented a determination coefficient (r2) of 0.999, calculated by the least square method. No interferences of the oil core or the gelling excipients were detected. The R.S.D. values for intra- and inter-day precision experiments were lower than 2%. The recovery ranged from 99.42% to 100.72%. Finally, the proposed method was successfully applied to determine coumestrol incorporated in the proposed topical formulations.

Development and characterization of parenteral nanoemulsions containing thalidomide.

This study reports the development of nanoemulsions intended for intravenous administration of thalidomide (THD). The formulations were prepared by spontaneous emulsification method and optimized with respect to thalidomide (0.01-0.05%, w/w), and hydrophilic emulsifier (polysorbate 80; 0.5-4.0%, w/w) content. The formulations were evaluated concerning physical appearance and drug crystallization; droplet size; zeta potential and drug assay. Only the formulation containing 0.01% THD and 0.5% polysorbate kept its properties in a satisfactory range over the evaluated period (60 days), i.e. droplet size around 200nm, drug content around 95% and zeta potential around -30mV. The transmission electron microscopy revealed emulsion droplets almost spherical in shape confirming the results obtained by photon correlation spectroscopy. Drug crystallization observed for higher content (THD 0.05%, w/w) nanoemulsions was investigated. The crystals observed at optical microscopy presented a different crystal habit compared to that of the raw material used. It was speculated whether the kind of THD polymorph employed could influence nanoemulsion formulation. Formulations were prepared with either one of THD polymorphs (ß- or α-) and crystals were characterized by fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD). It was observed that regardless of the polymorph employed (ß- or α-), drug crystallization occurs in the α-form. THD solubility in oils was not influenced by the polymorphic form. In addition, the in vitro dissolution profile of the selected formulation (THD 0.01%, w/w; polysorbate 0.5%, w/w) was assessed by bulk-equilibrium reverse dialysis sac technique and demonstrated a release profile similar to that of a THD acetonitrile solution, with around 95% THD being dissolved within 4h. Finally, a pharmacokinetic simulation of an intravenous infusion of 250mL of the selected nanoemulsion suggests that the parenteral administration of a dose as low as 25mg might lead to therapeutic plasma concentrations of thalidomide.

Development of topical nanoemulsions containing quercetin and 3-O-methylquercetin.

This study describes the physico-chemical properties and the skin permeation profile of quercetin (Q) and 3-O-methylquercetin (MQ) from lipid nanoemulsions. Formulations composed of octyldodecanol, egg lecithin, water (NE) and cetyl trimethyl ammonium bromide (CNE) were obtained by spontaneous emulsification. This procedure yielded monodisperse nanoemulsions exhibiting a mean droplet size of approximately 200-300 nm. Nanoemulsions were further characterized in terms of zeta-potential, surface tension, and morphology by transmission electron microscopy. The amount of flavonoids incorporated into nanoemulsions reached nearly 100% (at 1 mg/mL). The permeation studies were carried out using ear pig skin mounted in Franz diffusion cells. The overall results have shown a slow permeation profile of both Q and MQ from nanoemulsions. However, a higher permeation flux rate of flavonoids from CNE (approximately 0.2 microg/cm2/h) as compared to NE (approximately 0.08 microg/cm2/h) was observed, showing the effect of the positively charged surface of CNE on this parameter. Such results open interesting perspectives for the topical administration of the flavonoids Q and MQ.